Here's a brief shooting test of the Celcius CTW MX4 which is wearing a rare tan colour which means this could have been a custom paint job. The CTW MX4 has enhancements with the CASS gearbox, having a 3-round burst feature with its advanced ECU. It also has a working bolt release which, upon emptying the magazine, will stop the gun from firing. A battery low level indicator via an LED light is also part of this newest CTW from Celcius Technology.